Analog-to-digital converters (ADCs) are widely used, and are designed to sample and quantize input voltages via comparison against reference voltages. The reference voltages may each represent binary data values. Capacitors often serve as memory elements to hold the sampled input voltages to be processed. The successive approximation routine (SAR) ADC is one possible type of data converter, though others are possible, including pipelined ADCs. Commonly assigned U.S. Pat. No. 6,667,707B2, which describes a ground based voltage sampling approach for a SAR ADC, in which the reference plates of the sampling capacitors connect to ground during sampling, is hereby incorporated by reference in its entirety. Commonly assigned U.S. Pat. No. 7,167,121B2, which describes split reference voltage sampling to generate a reference voltage between positive supply voltage TVDD and ground for a SAR ADC, is hereby incorporated by reference in its entirety.